Isolation Pads for Bookshelf type speakers on stands. Do they work?

[shaiP]

I have a pair of JBL 5 inch speakers on 43" stands made of MDF.
I just put some isolation pads(1.5"-2" foam pads) between the speakers and the stand.
It feels like the bass is tighter/decays faster.
There are still vibrations felt around the base of the stand i.e. they are not zero.

To play devils advocate, It occurred to me that maybe I am hearing an "improvement" from my 25$ foam pads just like someone would from 2000$ cables i.e. its mostly placebo?
I would love to hear from you guys how can a "piece of foam" improve sound and How could this be measured with say a UMIK microphone and REW. Thank you so much.

 

[MalVeauX]

Hi,

It's decoupling. The vibrations are transferred from the cabinet contact to the stand. If the stand is hollow, it can cause all kinds of stuff. It's the same reason people have spikes on their speakers on carpet, and rubber feet on their speakers on hard surface. Decoupling. And you should notice it mostly, audibly, in bass like you did.

Another good way to isolate, without foam, is blue tac. It will decouple just as well, but also keep the speaker from falling off from a random bump. It's a better "long term" decoupling solution for a bookshelf on a stand.

As for measuring it, just do a sweep from 30hz to 700hz (+/- to your preference) in high resolution with your UMIK-1 in REW. Make sure to adjust the microphone height to the speaker at the same position after you add/remove the isolation foam so that it's recording as close to the same position each time so you can see the differences. Don't apply any smoothing. Post your two graphs.

If you're near a wall, based on what your graph shows, the next step is likely to apply treatment near by... but instead of doing it blindly, it's best to see what's going on with your response curve by measuring it (looking for nulls, modes, reflections, etc).

Very best,

 

[shadyJ]

Probably a placebo. To see the difference in REW, you simply have to measure the response. Any change would show the efficacy of your platform thingy.

 

[ryanosaur]

The chances of a standmount speaker creating vibrations that could mechanically be transmitted are so unlikely as to be pointless to pursue.
I fill my stands hollow legs with Sand to lower the center of gravity, thus making them more sturdy.
Yes, if you whack the metal leg, empty, with a wrench or hammer... it rings. But I've never heard the hollow leg ring!
Sand does have the added benefit of dampening that energy, yet I still would contend that it is not really a big factor in most scenarios.

I use an inexpensive foam isolation pad on the stand, not because I'm worried about transferring mechanical energy, but to protect the finish of my speaker from the metal top plate.

Just to correct something said above:
Floor spikes DO NOT decouple; quite the opposite. Floor spikes are designed to punch through carpet and contact the floor board which assists in stabilizing whatever is attached. Spikes COUPLE which simple physics would clearly show as you have solid points of contact.
They can be mounted to a platform that will help absorb mechanical energy such as a thick Maple or Granite.
More efficacious than that is isolating between the platform and the speaker. But this is only of real consequence if the speaker is capable of producing strong low frequency energy and should not be a concern for anything above subwoofer range.

 

[Trell]

The chances of a standmount speaker creating vibrations that could mechanically be transmitted are so unlikely as to be pointless to pursue.
...

I'd say: It depends!

 

[ryanosaur]

I'd say: It depends!

True... it is possible and I didn't completely rule that out!

 

[ryanosaur]

...I think one of the things that people often forget is that the wavefront itself is energy, and no amount of coupling or decoupling (or any combination thereof) can prevent that acoustic energy from vibrating items in the environment.

 

[Trell]

True... it is possible and I didn't completely rule that out!

Most of us have less than an ideal environment for listening and vibrations is an issue. I have changed the way I do an Audyssey calibration due to vibrations.

 

[Trell]

...I think one of the things that people often forget is that the wavefront itself is energy, and no amount of coupling or decoupling (or any combination thereof) can prevent that acoustic energy from vibrating items in the environment.

This is why I remove some items from my living room before calibration or measurements as they cause an audible ringing. A shaky standmount can do the same, though not audible to me.

 

[ryanosaur]

All true, @Trell . My floor is a suspended wood trampoline. A butterfly could land and everything moves!
Everything I've done in my room (from a combination of Coupling and Isolating 4 different bass cabinets, making certain that my Center and Surrounds are as dampened as possible, and even using neoprene washers in between the bolts of my wall mounted Rears) was done with an eye towards helping minimize any structural vibration.
In most circumstances, it works great, until the acoustic energy takes over and becomes the dominant force.
With the exception of the Outriggers with Spikes mounted to concrete platforms and the Soundpath Isolation feet I use on my bass cabinets... nothing cost more than $7-8 per speaker to implement.

But the nice thing about MDF for speakers and Baltic Birch for Subs is that the material does a very good job of dampening itself, assuming the cabinet is designed well. It often doesn't take much more than a simple cross brace in a Speaker to prevent unwanted energy from affecting it. The larger and deeper the extension, obviously the more such bracing needs to be upgraded.
That said, most OEM gear these days is pretty solid.
In my mind, it's not the primary pursuit, rather a secondary one to consider after proper set up in ones room is finalized. Unless, that is, you are aware of a structural concern up front, as I was with my floor.

 

[lovinthehd]

I'm betting more on the placebo side of things.

 

[zieglj01]

I use some with my modified Cambridge S30 speakers, but mainly to raise the speakers -- and I may be getting 5% better sound ... but rubber bumper feet will also decouple the sound ... As the Audio World Turns

 

[Teetertotter?]

Any thing wrong with bookshelf, FL/FR speakers w/o feet, resting on wood tables? Are my EARS going to be that acute that I could not tell the difference, if used rubber feet on the speakers undersides??

Also, my subwoofer is squarely resting on carpet.

Please tell me I will notice a big difference???? With raising speakers off the surfaces.

 

[ryanosaur]

No. Your ears won’t fall off. And there is nothing inherently wrong with it.
If you are experiencing any annoying rattles or vibrations, fold up a couple towels and put one under each speaker to see if that is the cause.

 

[zieglj01]

Any thing wrong with bookshelf, FL/FR speakers w/o feet, resting on wood tables? Are my EARS going to be that acute that I could not tell the difference, if used rubber feet on the speakers undersides??

Putting something under can help to protect the bottom from scratches

 

[Teetertotter?]

No. Your ears won’t fall off. And there is nothing inherently wrong with it.
If you are experiencing any annoying rattles or vibrations, fold up a couple towels and put one under each speaker to see if that is the cause.

Ya, that is basically what I thought, w/o professional graph measurements. lol I watch a lot of DD movies, TV shows and some internet mp3. My ears say I don't have an issue with my speakers. lol My equipment is properly adjusted to make music to MY EARS, in my basic room. Graph measurements do mean a lot to some people. There are some interesting YOU TUBE videos on the subject. But, maybe those that are music lovers, have that acute ear level to tell a difference??? Or equipment is not properly configured.

 

[MalVeauX]

Any thing wrong with bookshelf, FL/FR speakers w/o feet, resting on wood tables? Are my EARS going to be that acute that I could not tell the difference, if used rubber feet on the speakers undersides??

Also, my subwoofer is squarely resting on carpet.

Please tell me I will notice a big difference???? With raising speakers off the surfaces.

Hi,

Depends on the size of the table/surface, as it can of course be a reflection point. Small vibration can cause abrasion to the finish of both the speaker and/or table surface, if you care about that, maybe.

Very best,